Thermoelectric conversion devices are used to convert engine waste heat, such as engine exhaust heat, into electricity.
One example system using such a device is provided by U.S. Pat. No. 7,178,332 to Sasaki. In this system, heat from the engine exhaust is harvested by a heat recovery portion coupled to an engine exhaust passage. The harvested heat is then transferred to a thermoelectric conversion device via a first heat pipe and to a downstream catalyst to warm up the catalyst via a second heat pipe. The heat pipes are designed in such ways that the engine exhaust heat is transferred to the thermoelectric conversion device only after the catalyst has been warmed up to its activation temperature.
However, the inventors herein have recognized that under certain conditions, the temperature of the heat sources may become too high, exceeding conversion capacity of the thermoelectric conversion devices and/or causing damages to the thermoelectric conversion devices. Specifically, if the temperature of the engine exhaust becomes too high, the excess heat may damage the thermoelectric conversion device.
To at least partially address the above mentioned issues, systems and methods for converting engine heat energy to electricity using a thermoelectric conversion device are provided herein. One example system may include an engine heat source, a thermoelectric conversion device for converting heat into electricity, and a heat pipe having a first end and a second end and configured to transfer heat received at the first end to the second end, the first end interposed between the engine exhaust passage and the thermoelectric conversion device, the second end disposed in a heat sink.
One example method may include passing exhaust gas through a passage in an engine exhaust passage, transferring thermal energy from the exhaust gas to a thermoelectric conversion device for converting thermal energy into electricity, and transferring thermal energy from the exhaust gas and away from the thermoelectric conversion device via a heat pipe to a heat sink when temperature at a first end of the heat pipe coupled to the exhaust passage is greater than a threshold temperature.
In this way, when the temperature of the engine exhaust is too high, for example, the excess heat may be transferred away from the thermoelectric conversion device to the heat sink via the heat pipe, thus reducing potential heat damage to the thermoelectric conversion device.
In some examples, a second thermoelectric conversion device or a heating system for heating one or more components of the vehicle is provided as the heat sink for the first heat pipe, allowing the engine waste heat to be more efficiently used. In addition, a second heat pipe may be provided to transfer excess heat away from the second thermoelectric conversion device or the heating system to reduce overheating of the second thermoelectric conversion device or the heating system.
This Summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. Furthermore, the claimed subject matter is not limited to implementations that solve any or all disadvantages noted in any part of this disclosure.